Study on memory characteristics of fin-shaped feedback field effect transistor

Abstract

The nonvolatile and volatile memory characteristics of feedback field-effect transistors (FBFETs) with nitride charge storage layers were theoretically studied. Because of the electrons and holes stored in the nitride layer, the threshold voltage (V (TH)) window of 0.6 V was opened/observed. And, with the help of the formation of a positive feedback loop in the p(+)-n(+)-p-n(+) doped silicon region in FBFET, it turned out that the read delay time of the FBFET for nonvolatile memory applications can be shorter than 1 ns. On the other hand, for the volatile memory applications, the FBFET can implement (a) non-destructive read operations owing to the self-sustaining feedback loop characteristic, and (b) a significantly long retention time which can suppress the power dissipation in refresh. Furthermore, the operation scheme of volatile memory mode can be simplified by setting gate voltage conditions for the hold and read operations to be identical to each other. The FBFET showed its on-state drive current of 6 x 10(-5) A mu m(-1) and the on-/off-current ratio of 10(9). The potential of merging nonvolatile and volatile memory devices in a single cell is discussed and demonstrated in this work.